1. Field of the Invention
The present invention relates to a semiconductor device having external contact terminals and a method for using the same and, particularty to a semiconductor device having external terminals, such as a semiconductor socket having a number of springy external contact pins or terminals of a micro-spring system, which are used while being brought into contact with pads or solder balls of an interposer or a connector board.
2. Description of the Related Art
In the prior art, in a semiconductor device having a number of springy external contact pins or terminals of a micro-spring type, used as a test probe or otherwise, the external contact pin or terminal is made, for example, of a gold (Au) wire for bonding, which surface is plated with palladium (Pd), indium (in) or others. In such a semiconductor device, while the contact terminals repeat making contact with pads or solder balls on an interposer or a connector board several hundreds or thousands times, a surface of the terminal may be become contaminated or adhered with dirt or solder transferred from the mating object, which increases the electric contact resistance of the external terminal, causing a problem particularly in a high-frequency probe pin in that a test signal is not accurately transmitted even if the adhered solder is slight in amount.
In general, a terminal portion of the semiconductor socket of this kind used as a probe pin is periodically rinsed. However, even though the rinsing is carried out, it is difficult to completely remove the dirt which has been once adhered. Accordingly, there is a problem in that the contact resistance is difficult to maintain at a low level in a stable manner for a long period, which means that the device is not durable against a long term use in a stable state. In addition, as the semiconductor device or the like is generally expensive, it is not economical to frequently replace it with a new one.
There have been various prior arts related thereto as follows. When a laminated film of copper and tin/copper alloy is formed by a single electrolytic plating bath, the plating is carried out in such a manner that an electric potential at which copper is deposited and that at which copper and tin are deposited together are alternately and pulsatively applied to the plating bath (Japanese Unexamined Patent Publication No. 2002-256482); a copper (Cu) layer and an indium (In) layer are alternately formed on a surface of an object to be plated (Japanese Unexamined Patent Publication No. 2002-256478); a wire forming a contact terminal is coated, for example, with a resin so that a tip end of the wiring is exposed from the resin (Japanese Unexamined Patent Publication No. 2000-200804); electrolytic gel is used for removing an unnecessary solder layer or an oxide layer thereof adhered or deposited onto a surface of a contact portion of an IC socket without detaching the IC socket from a printed circuit board (Japanese Unexamined Patent Publication No. 2001-9398); an abrasive layer is provided on a plate-like elastic member of an IC socket to compensate the deterioration of contacts by the opening/closing operation (Japanese Unexamined Patent Publication No. 11-233220); an electrode of an IC socket is dipped in a solder-removal liquid with an acidic agent, rinsed with pure water, and then dried (Japanese Unexamined Patent Publication No. 7-234262); and a pair of terminals are provided so that one of them is brought into contact with the upper surface of a support board generally parallel thereto (Japanese Patent Publication No. 2892505).
As described above, in the prior art external contact pin or terminal of a micro-spring system, the surface thereof is variously treated or plated for the purpose of preventing the electric contact resistance from increasing due to the contamination or the adhesion of foreign matter on the surface. However, a method has not yet been found by which the external pin could be used in a stable state for a long period even if the contact is repeated several hundreds or thousands times.